Re: [PATCH v2 2/3] tty: serial: sh-sci: Add RZ/G2L SCIF DMA tx support

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Hi Biju,

On Fri, Mar 24, 2023 at 11:02 AM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> Add SCIF DMA tx support for RZ/G2L alike SoCs.
>
> RZ/G2L alike SoC use the same signal for both interrupt and DMA
> transfer requests, so we must disable line interrupts(tx and tx end)
> while transferring DMA and enable the TIE source interrupt.
>
> Based on a patch in the BSP by Long Luu
> <long.luu.ur@xxxxxxxxxxx>
>
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>

Thanks for your patch!

> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -172,6 +172,13 @@ to_sci_port(struct uart_port *uart)
>         return container_of(uart, struct sci_port, port);
>  }
>
> +static inline bool is_rz_scif_port(struct uart_port *port, struct sci_port *s)
> +{
> +       const struct plat_sci_port *p = s->cfg;
> +
> +       return port->type == PORT_SCIF && p->regtype == SCIx_RZ_SCIFA_REGTYPE;

The latter implies the former, so you can drop the first check.
After that, the check becomes sufficiently simple to inline?

> +}
> +
>  static const struct sci_port_params sci_port_params[SCIx_NR_REGTYPES] = {
>         /*
>          * Common SCI definitions, dependent on the port's regshift
> @@ -588,6 +595,16 @@ static void sci_start_tx(struct uart_port *port)
>
>         if (s->chan_tx && !uart_circ_empty(&s->port.state->xmit) &&
>             dma_submit_error(s->cookie_tx)) {
> +               if (is_rz_scif_port(port, s)) {
> +                       /* Switch irq from SCIF to DMA */
> +                       disable_irq(s->irqs[SCIx_TXI_IRQ]);
> +                       disable_irq(s->irqs[SCIx_TEI_IRQ]);
> +
> +                       /* DMA need TIE enable */
> +                       ctrl = serial_port_in(port, SCSCR);
> +                       serial_port_out(port, SCSCR, ctrl | SCSCR_TIE);

Enabling TIE is also done for SCIFA below (out of visible context).
Perhaps you can combine?

> +               }
> +
>                 s->cookie_tx = 0;
>                 schedule_work(&s->work_tx);
>         }
> @@ -1214,9 +1231,16 @@ static void sci_dma_tx_complete(void *arg)
>                 schedule_work(&s->work_tx);
>         } else {
>                 s->cookie_tx = -EINVAL;
> -               if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) {
> +               if (port->type == PORT_SCIFA || port->type == PORT_SCIFB ||
> +                   is_rz_scif_port(port, s)) {
>                         u16 ctrl = serial_port_in(port, SCSCR);
>                         serial_port_out(port, SCSCR, ctrl & ~SCSCR_TIE);
> +                       if (port->type == PORT_SCIF) {

"if (s->cfg->regtype == SCIx_RZ_SCIFA_REGTYPE)"?

> +                               /* Switch irq from DMA to SCIF */
> +                               dmaengine_pause(s->chan_tx_saved);
> +                               enable_irq(s->irqs[SCIx_TXI_IRQ]);
> +                               enable_irq(s->irqs[SCIx_TEI_IRQ]);
> +                       }
>                 }
>         }

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds



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